Super-fast home broadband connections now mean we can surf faster and access much richer content than ever before. But how much is enough? And do we really need all that speed? Spencer Kelly investigates.

Data flows along broadband rather like a network of rivers

The internet is a network of pathways and connections, criss-crossing the world.

Data flows along them like water along rivers.

But we are all craving more data, and the internet service providers are finding ways to get more and more data down the lines into our homes.

Where older, dial-up connections achieved data rates of thousands of bits, or kilobits, per second, newer broadband connections can reach speeds of millions, or megabits, per second (mbps).

The fastest home broadband connection currently available in the UK is 8 mbps, but this speed is by no means record-breaking.

In South Korea, super-fast broadband is a way of life, and one French service offers 20 mbps.

With a super-fast connection, downloading will not be necessary

Rupert Goodwins, a technology commentator for ZDNet, says: "High-speed broadband access is going to be most useful for high-definition video, and the delivery of other media content, like movies, very quickly.

"By and large, e-mail and web browsing are going as fast now as they'll ever go.

"But super-fast broadband is the next step, what the Americans call a rich-media world, where you don't wait for your movies - they just appear when you want to watch them."

Using high-speed broadband, a 76 MB video file downloads in less than two minutes.

Using a dial-up connection, it would have taken more than three hours.

In fact, with a fast enough connection, you do not have to download the movie at all.

The Home Choice on-demand movie and music service stores the movie on the provider's servers, and streams it down a broadband connection to your TV in real-time, in full television quality.

Slow flow

But faster connections do not guarantee improved performance.

When there is not enough water even wide riverbeds will only hold a trickle.

Similarly, super-fast broadband will still go slow if the data is not sent fast enough to fill it.

Chris Sterling, of UK Online, explains: "Even though you may have a super-fast broadband connection in your home, if you're downloading from a very remote or a very slow site then that will obviously be a limiting factor."

Even if you are streaming from a very fast site, most web content is currently optimised to suit the more common, slower connection speeds.

For example, the broadband version of Click Online only streams at 225 kbps, leaving most of a super-fast connection redundant.

Upload limitations

Some applications do not just involve receiving data. You have to send it too.

Slow upload speeds mean video conferencing is usually low quality

Take video conferencing for example, where both parties are sending just as much data as they are receiving.

Here, the data transfer rate is limited by your upload speed, which is usually a lot slower than the advertised download speed.

Hence the pictures are still small and a little jerky.

As Rupert Goodwins says: "The weak link is going to be their upload.

"It doesn't matter how fast you can download; you're not getting it faster than they can send it.

"This is true for individuals talking to individuals. It's less true for getting stuff off big websites, because they tend to have very fat pipes to the internet.

"There the bottleneck comes if everyone is trying to get the same file at once."

'Locked' internet

If too many users want the same data at the same time, parts of the internet itself could clog up.

Matt Beal, from BT's 21st Century Network Project, says that exactly what would happen is a little bit hard to predict.

"But, fundamentally, everyone would cease to get anything. You would have a situation where the internet locks up.

"It wouldn't burn out, it wouldn't do anything, it would simply lock up and very few, if any, people would have their needs met."

So even if you have a very fast connection, there could be other factors that limit the speed of your web experience.

Here is a recap of what to expect with super-fast broadband:

Surfing/downloadingAlways faster

Assuming the server at the other end can handle it, downloading files will always be faster. Surfing will also be faster, although most websites contain so little data you will only be saving fractions of seconds.

Video conferencing/Internet phone calls/p2pLimited by upload speeds

If you are sending as much data as you are receiving, as in video conferencing, internet phone calls, or peer-to-peer file sharing, you are limited by both parties' upload speeds.

High-speed broadband really comes into its own when you are networking several computers in your home - then you can share a very high-speed connection between several users.

In the near future, high-definition television, with higher resolution and much more data, could need 10-20 mbps.

The good news is that the internet is constantly growing, with new cables and optic fibre being laid all the time, as Matt Beal says.

"We have learned to get more and more out of fibre since its introduction in the eighties than we ever thought possible.

"Where fibre used to have less than 1 gbps capacity we now expect that same fibre strand to be able to drive hundreds and hundreds of gbps capacity out of the same fibre.

"That's what interesting, scary and exciting about telecommunications today."

Click Online is broadcast on BBC News 24: Saturday at 2030, Sunday at 0430 and 1630, and on Monday at 0030. A short version is also shown on BBC Two: Saturday at 0645 and BBC One: Sunday at 0730 . Also BBC World.